1. Field of the Invention
The present invention relates to a ladle cover for a metallurgical vessel. The cover has provisions for collecting fumes and vapors from the upper periphery of the vessel. The present invention finds particular application in the production and/or processing of leaded steel during which hazardous lead-containing fumes are typically emitted.
2. Description of Related Art
It is often desirable to access the contents of a covered metallurgical vessel, such as to introduce alloying elements, air, or other gases. Accordingly, prior artisans have provided covers with openings to accommodate such passage of materials. Collin illustrated a ladle cover having an upwardly extending member for the passage of air, and an opening for receiving and discharging metal in U.S. Pat. No. 429,337. Other aspects of modern vessel cover construction include a lightweight ladle lid design such as disclosed by Heyer et al. in U.S. Pat. No. 4,834,346. Lift brackets have also been provided for such covers, as illustrated by Reighart in U.S. Pat. No. 2,774,123.
During the production of particular alloyed metals, such as for example, leaded steel, hazardous fumes or vapors are often emitted from various components used in the production process. Efforts have been taken to collect such harmful fumes, such as described in U.S. Pat. No. 4,724,895 to Mulesa. Mulesa and other artisans have directed efforts to collecting fumes emitted during and after casting. That is, the prior art has primarily focused on collecting fumes emitted from components during and after casting molten material, such as leaded steel.
A significant amount of harmful, or potentially harmful, fumes may still escape from a metallurgical process prior to casting, even a process utilizing state of the art fume collection equipment. Accordingly, there is a need for a technique and associated hardware by which potentially harmful fumes, or at least a significant proportion of such fumes, may be collected from process components containing the molten metal prior to casting. More particularly, there is a need for a technique and related equipment for collecting hazardous fumes emitted from a metallurgical vessel, such as a ladle.
In addition to the foregoing, another concern in the design of a cover for a metallurgical vessel is minimizing heat loss through the cover. This is particularly significant for applications in which the vessel is a ladle utilized to receive molten metal. Prior artisans have incorporated heat resistant refractory materials along the underside of covers such as disclosed in U.S. Pat. No. 2,122,032 to Goldberg et al. Although satisfactory in most respects, it would be desirable to provide a vessel cover having improved heat retention qualities, i.e. relatively low rates of heat transfer through the cover.